Heat the oil in a large pan,add the onion, bacon, celery and carrots and cook over a medium heat for about 7-10 mins, stirring occasionally until vegetables have softened.,______,Bring the mixture to the boil, then reduce the heat and cover the pan.,Simmer gently for about 20-30 minutes,until the vegetables are tender.,Remove the pan from the heat and puree the soup in a liquidiser or food processor, or use a stick blender.,Add seasoning to taste.,Leave to cool, then pour it into a freezer container, cover and label.,Will freeze for up to 3 months.,To serve: Allow the soup to defrost overnight, then bring to the boil before serving.,Cut the rashers of bacon into strips and cook them in a hot frying pan until crisp and place on top of the soup, with a couple of small sprigs of thyme.,Sprinkle some freshly ground black pepper over.